U.S. patent application number 12/304845 was filed with the patent office on 2009-11-12 for radiant heater.
Invention is credited to Fermin Adames, SR., Enoch A. Zenteno.
Application Number | 20090279879 12/304845 |
Document ID | / |
Family ID | 38832893 |
Filed Date | 2009-11-12 |
United States Patent
Application |
20090279879 |
Kind Code |
A1 |
Zenteno; Enoch A. ; et
al. |
November 12, 2009 |
RADIANT HEATER
Abstract
A radiant heater includes a heater body having a box-like
configuration, the body defining an inner cavity and including a
base wall and an open end opposite the base wall. The body is
fabricated from a ceramic material. The body also includes a
heating element extending a length of the body and positioned to
direct energy through the open end of the body.
Inventors: |
Zenteno; Enoch A.; (Oak
Park, IL) ; Adames, SR.; Fermin; (Inverness,
IL) |
Correspondence
Address: |
MICHAEL BEST & FRIEDRICH LLP
Two Prudential Plaza, 180 North Stetson Avenue, Suite 2000
CHICAGO
IL
60601
US
|
Family ID: |
38832893 |
Appl. No.: |
12/304845 |
Filed: |
June 15, 2007 |
PCT Filed: |
June 15, 2007 |
PCT NO: |
PCT/US07/71306 |
371 Date: |
December 15, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60814268 |
Jun 16, 2006 |
|
|
|
Current U.S.
Class: |
392/416 |
Current CPC
Class: |
F26B 3/28 20130101; H05B
3/008 20130101; F24C 7/043 20130101; H05B 2203/032 20130101 |
Class at
Publication: |
392/416 |
International
Class: |
H05B 3/00 20060101
H05B003/00 |
Claims
1. A radiant heater comprising: a heater body having a box-like
configuration, the body defining an inner cavity and including a
base wall and an open end opposite the base wall, wherein the body
is fabricated from a ceramic material; a heating element extending
a length of the body and positioned to direct energy through the
open end of the body.
2. The radiant heater of claim 1 wherein the ceramic material is an
ultra-low thermal expansion material.
3. The radiant heater of claim 1 wherein the base wall of the body
includes at least one aperture for dispersing fumes that accumulate
in the inner cavity.
4. The radiant heater of claim 1, and further comprising a
reflector positioned between the base wall of the body and the
heating element wherein the reflector re-directs energy from the
heating element through the open end of the body.
5. The radiant heater of claim 1 wherein the heating element
includes a wire element contained within a quartz tube.
6. The radiant heater of claim 5 wherein the quartz tube is
translucent.
7. The radiant heater of claim 5 wherein the quartz tube is a ruby
quartz tube.
8. The radiant heater of claim 5 wherein the wire element is
selected from a group consisting of a resistance wire element, a
halogen-tungsten element and a carbon element.
9. The radiant heater of claim 8 wherein the resistance wire
element is formed from a ferritic alloy.
10. The radiant heater of claim 1 wherein the heating element
selected from the group consisting of a short-wave heating element,
a medium-wave heating element and a long-wave heating element.
11. The radiant heater of claim 1 wherein the heating element
includes a plurality of heating elements extending the length of
the body.
12. The radiant heater of claim 11 wherein each heating element
includes a wire element contained within a quartz tube.
13. The radiant heater of claim 12 wherein the quartz tube is a
twin bore tube, each bore containing one wire element.
14. The radiant heater of claim 11 wherein at least one of the
heating elements is a short-wave heating element and at least one
of the heating elements is a medium-wave heating element.
15. The radiant heater of claim 1, and further comprising a pair of
supports plate extending across a width of the body at opposite
ends of the body wherein the support plates hold the heating
element in position.
16. The radiant heater of claim 1, and further comprising a element
holders positioned at opposite ends of the heater body and coupled
to the base wall of the body, wherein each element holder couples
one end of the heating element to the body.
17. A radiant heater comprising: a heater body having a box-like
configuration, the body defining an inner cavity and including a
base wall and an open end opposite the base wall, wherein the body
is fabricated from a ceramic material; a heating element extending
a length of the body and positioned to direct energy from through
the open end of the body; and a reflector positioned between the
base wall of the body and the heating element wherein a reflective
surface of the reflector re-directs energy from the heating element
through the open end of the body.
18. The radiant heater of claim 17 wherein the reflector is
substantially planar.
19. The radiant heater of claim 17 wherein the reflector has a
substantially parabolic shape.
20. The radiant heater of claim 17 wherein the reflective surface
of the reflector includes a dome-like pattern.
21. The radiant heater of claim 17 wherein the reflective surface
of the reflector includes a white reflective coating.
22. The radiant heater of claim 17 wherein the reflective surface
of the reflector includes a gold reflective coating.
23. The radiant heater of claim 17 wherein the heating element
includes a plurality of heating elements extending the length of
the body.
24. The radiant heater of claim 23 herein at least one of the
heating elements is a short-wave heating element and at least one
of the heating elements is a medium-wave heating element.
25. The radiant heater of claim 17 wherein the heating element is
selected from the group consisting of a short-wave heating element,
a medium-wave heating element and a long-wave heating element.
26. The radiant heater of claim 17, and further comprising a pair
of support plates extending across a width of the body at opposite
ends of the body wherein the support plates hold the heating
element and the reflector in the body.
27. The radiant heater of claim 17, and further comprising a pair
of element holders positioned at opposite ends of the heater body
and coupled to the base wall of the body, wherein each element
holder couples one end of the heating element to the body.
28. The radiant heater of claim 27 wherein a slot is defined
between each element holder and the base wall, the reflector being
retained within the slots.
29. An industrial heating system for use in drying or heating
processes, the heating system comprising: a housing for positioning
adjacent a process path for a process material; a radiant heater
housed within the housing and directed towards the process path,
the radiant heater comprising, a heater body having a box-like
configuration, the body defining an inner cavity and including a
base wall and an open end opposite the base wall, the open end
directed towards the process path, wherein the heater body is
formed from a ceramic material, a heating element extending a
length of the body and positioned to direct energy through the open
end of the body, and a reflector positioned between the base wall
of the body and the heating element wherein a reflective surface of
the reflector re-directs energy from the heating element through
the open end of the body.
30. The heating system of claim 29, and further comprising a
mounting head for coupling the radiant heater to the housing, the
mounting head coupled to an exterior surface of the base wall and
an interior surface of the housing.
31. The heating system of claim 29, and further comprising at least
one aperture for dispersing fumes that accumulate in the inner
cavity.
32. The heating system of claim 29 wherein a plurality of radiant
heaters are within the housing and directed towards the process
path.
33. The heating system of claim 32 wherein the heating element of
at least two radiant heaters have different wavelengths.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Patent Application No. 60/814,268, entitled "Radiant Heater," filed
Jun. 16, 2006 by Enoch A. Zenteno and Fermin Adames Sr.
BACKGROUND
[0002] This invention relates to heating elements and, more
particularly, to ceramic, infrared-radiant heaters.
[0003] Heat transfer may be accomplished through convection,
conduction and radiation. As is known, convection is heat transfer
by mass motion of a medium such as air or water when the heated
medium is caused to move away from the source of heat, carrying
energy with it; conduction is heat transfer by means of molecular
agitation within a material without any motion of the material as a
whole; and radiation is heat transfer by the emission of
electromagnetic waves that carry energy away from the emitting
object. Of the foregoing, radiation is the most efficient and
flexible heat transfer means, and is adaptable to a variety of
applications.
[0004] Industrial infrared heaters are generally classified by type
(e.g., short, medium and long wavelength) based on the position of
the maximum emission or peak wavelength in their spectral radiant
power distribution. This categorization is based solely on the
temperature of the heating element itself and by the application of
Wien's displacement law. In other words, a short-wave heater is
classified as such because its coil can reach steady state
temperatures between 2148.degree. F. (2 .mu.m) and 6060.degree. F.
(0.8 .mu.m); similarly, a medium-wave heater's coil temperatures is
capable of reaching between 845.degree. F. (4 .mu.m) and
2148.degree. F. (2 .mu.m); and finally, a long-wave heater has coil
temperatures less than 845.degree. F. (or .lamda..sub.max>4
.mu.m).
[0005] Radiant heating elements are typically used in applications
where directional or focused heating is required. To this end, as
is known, quartz heaters include elongated tubes and metal
reflectors, and ceramic heaters are formed as curved or flat
panels. Some processes used to manufacture heaters limit the shapes
that the heaters may assume. Processes have been developed to
produce heaters having non-standard shapes, but such processes have
limitations on the internal construction of such heaters. These
limitations on internal construction do not provide a heater having
the highest potential efficiency. Yet other processes only allow
for the production of a single type of heater (i.e., the process is
capable of only producing a heater that radiates in a 180.degree.
range or a heater that radiates in a 360.degree. range, not
both).
[0006] Infrared radiation is absorbed by organic molecules and
converted into molecular vibration energy. When the radiant energy
matches the energy of a specific molecular vibration, absorption
occurs. In one embodiment, an efficient infrared heating system
comprises a set of infrared heaters with the emissive wavelengths
finely tuned to match the absorption wave-lengths for a given
application at its various stages of the heating process. That is,
as the drying process progresses and the absorption wavelength of
the material changes, the emissive wavelength changes accordingly,
as shown in FIG. 1.
[0007] Referring to FIG. 1, Zone A of the system, near the entrance
of the conveyor system, or process path, may contain short-wave
heaters operating at near 2 .mu.m to match the first peak of the
absorption spectra for water (around 95%). In the middle of the
heating application (i.e., Zone B), medium-wave heaters may be
employed to match the second highest absorption peak (around 94%).
Finally in Zone C, close to the end of the conveyor, just before
exiting the system, and to prevent a strong thermal shock for the
application material, long-wave heaters may be placed to match the
final high absorption peak (around 78%).
[0008] In a real-world application, however, the construction and
operation of such a system is very difficult to achieve because
there is no infrared heater in the industry that can deliver short,
medium or long waves as a single unit. Each heater type has unique
design, construction and operation requirements that make them very
difficult to combine with other types. For instance, the heat
output of a short-wave emitter is so high that often cooling
systems are required to maintain the heater's housing at
permissible levels.
[0009] Currently used industrial radiant heaters have two elements
in common, a reflective surface and a housing. Heaters provided by
Elstein-Werk M. Steinmetz GmbH & CO. KG (Germany) and Heraeus
Noblelight Inc. (Duluth, Ga.) both include a gold reflective
material directly applied to the housing and to the quartz
material, respectively. The direct application of the gold makes
the overall size of the heater smaller and easier to handle because
there is no need for a reflector (i.e., the body itself is a
reflector). However, the power generated by the heated element
cannot exceed a certain limit that would cause the gold to
evaporate (greater than 820.degree. C.). Further, there still is a
considerable amount of heat that the reflector will absorb and
conduct to the back-side of the heater, thereby heating up the
structure that holds the heater and not the application. Heaters by
Fostoria Industries (Fostroria, Ohio) and the Research Inc. (Eden
Prairie, Minn.) require a reflector embedded in a steel housing for
the heater to operate properly.
[0010] Another example of an industrial radiant heater includes a
ceramic infrared heater that is either solid or hollow. High
powered hollow heaters exhibit a tendency to develop cracks at the
outer shell as a result of thermal expansion mismatch between an
embedded coil layer and an outer shell. In simple heat transfer
terms, the Joule heating generated at the coil is transferred to
the surrounding ceramic layer by conduction. Because of the low
thermal conductivity of ceramics, the coil layer is impacted
significantly faster than the outer shell resulting in a large
temperature gradient between both layers, causing at the same time,
a large thermal expansion mismatch. In some cases, the tensile
strains exceed the strength of the body and visible cracks develop
to release the strain. These cracks form in either glazed or
unglazed ceramic bodies, and those with or without heads. Such
cracking suggests that the cracks were not induced by residual
stresses caused by the cooling glaze, but rather by the larger
expansion suffered by the coil layer during energization.
[0011] The challenge of designing an infrared heater that would
emit in all available wavelengths requires consideration of the
parameters of existing infrared units. Existing ceramic body
heaters with embedded ferritic alloys (FeCrAl) have a high
mechanical stability, but have maximum power limitations resulting
in microstructure fractures that induce dielectric failure in high
wattage/voltage units. Infrared heaters with quartz tubes enclosed
in sheet frame have a resistance coil that freely expands within
the tubes; however, the sheet metal structure is highly susceptible
to corrosion, distortion and deformation. Finally, tungsten-halogen
and carbon infrared lamps have a fast response time and provide
control and management of the emitter wavelengths, but such lamps
have limited assembly options.
SUMMARY
[0012] In one embodiment, the invention provides a radiant heater
including a heater body having a box-like configuration, the body
defining an inner cavity and including a base wall and an open end
opposite the base wall. The body is fabricated from a ceramic
material. The radiant heater also includes a heating element
extending a length of the body and positioned to direct energy from
through the open end of the body.
[0013] In another embodiment, the radiant heater includes a heater
body having a box-like configuration, the body defining an inner
cavity and including a base wall and an open end opposite the base
wall. The body is fabricated from a ceramic material. A heating
element extends a length of the body and is positioned to direct
energy from through the open end of the body. The radiant heater
also includes a reflector positioned between the base wall of the
body and the heating element, wherein a reflective surface of the
reflector re-directs energy from the heating element through the
open end of the body.
[0014] In yet another embodiment, the invention provides an
industrial heating system for use in drying or heating processes.
The heating system includes a housing for positioning adjacent a
process path for a process material and a radiant heater housed
within the housing and directed towards the process path. The
radiant heater includes a heater body having a box-like
configuration, the body defining an inner cavity and including a
base wall and an open end opposite the base wall, the open end
directed towards the process path. The heater body is formed from a
ceramic material. A heating element extends a length of the body
and is positioned to direct energy through the open end of the
body. The radiant heater also includes a reflector positioned
between the base wall of the body and the heating element, wherein
a reflective surface of the reflector re-directs energy from the
heating element through the open end of the body.
[0015] Other aspects of the invention will become apparent by
consideration of the detailed description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 illustrates an example of an infrared heating system
for a drying process.
[0017] FIGS. 2A and 2B illustrate a radiant heater according to one
embodiment of the invention.
[0018] FIGS. 3A-3C illustrate a radiant heater according to another
embodiment of the invention.
[0019] FIGS. 4A-4D illustrate a housing of the radiant heater
according to one embodiment of the invention.
[0020] FIG. 5 illustrates a housing of the radiant heater according
to one embodiment of the invention.
[0021] FIG. 6 illustrates a housing of the radiant heater according
to another embodiment of the invention.
[0022] FIGS. 7A-7B illustrate one embodiment of a flat reflector
for use with the radiant heater.
[0023] FIG. 8 illustrates one embodiment of a spring clip for use
with a mounting head of the radiant heater.
[0024] FIG. 9 illustrates one embodiment of a housing of the
radiant heater shown in FIGS. 2A-2C.
[0025] FIGS. 10A and 10B illustrate an embodiment of a radiant
heater including halogen-tungsten lamps.
[0026] FIGS. 11A and 11B illustrate an embodiment of a radiant
heater including a pair of halogen-tungsten lamps.
[0027] FIG. 12 illustrates another embodiment of a housing of the
radiant heater shown in FIGS. 2A-2B, 3A-3C, 10A-10B and
18A-18B.
[0028] FIG. 13 illustrates an end portion of the radiant heater
shown in FIG. 10A, including convection holes.
[0029] FIGS. 14A-14C illustrate an element holder according to one
embodiment of the invention.
[0030] FIG. 15 is a schematic illustration of a cross-section of
the radiant heater shown in FIG. 10A, including the element
holder.
[0031] FIGS. 16A-16B illustrate one embodiment of a parabolic
reflector for use with a radiant heater.
[0032] FIG. 17 illustrates one embodiment of a housing of the
radiant heater shown in FIGS. 11A-11B, 19A-19B and 21A-21B.
[0033] FIGS. 18A and 18B illustrate an embodiment of a radiant
heater including a carbon element.
[0034] FIGS. 19A and 19B illustrate an embodiment of a radiant
heater including two carbon elements.
[0035] FIGS. 20A and 20B illustrate an embodiment of a radiant
heater including three carbon elements.
[0036] FIGS. 21A and 21B illustrate an embodiment of a radiant
heater including a halogen-tungsten element and a carbon
element.
[0037] FIGS. 22A and 22B illustrate an embodiment of a radiant
heater including a halogen-tungsten element and carbon
elements.
[0038] Before any embodiments of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of components set forth in the following description or illustrated
in the following drawings. The invention is capable of other
embodiments and of being practiced or of being carried out in
various ways. Also, it is to be understood that the phraseology and
terminology used herein is for the purpose of description and
should not be regarded as limiting.
DETAILED DESCRIPTION
[0039] Infrared heaters are used in a variety of industrial and
medical applications for providing radiant heat in a drying or
heating process. Examples of industrial applications include
textile processing, food processing, thermoforming, film
processing, liquid processing, or the like. It is also possible to
use the infrared heaters as a radiant heat source, such as with
outdoor heating. Radiant heaters are generally housed in a
structural housing (e.g., FIG. 1), as is known in the art, and are
directed towards process material, often transported along a
process path. Examples of structural housings include a housing
that accommodates a single heater, an array housing that
accommodates a plurality of heaters along its length, a panel array
housing that accommodates a plurality of heaters in an array
configuration, or the like. Structural housings may be customized
based upon a user's specifications. For example, the heaters may be
utilized individually, or may be incorporated into a large assembly
containing any combination of the heaters described below.
[0040] A preferred embodiment of the present invention radiant
heater incorporates existing infrared technologies into a single
unit. The radiant heater is capable of accommodating
halogen-tungsten lamps (short-wave), carbon lamps (medium-wave,
fast response), resistance wire embedded in twin and single quartz
tubes (medium-wave and long-wave), as well as re-directing heat
towards a given application (i.e., provide directional heat). The
radiant heater can withstand thermal shock and provide high
mechanical stability at any operating temperature. Finally, the
radiant heater is compatible with industry-wide standard-size
infrared heaters.
[0041] FIGS. 2A, 2B, 3A, 3B and 3C illustrate a radiant heater 10
according to one embodiment of the invention. The radiant heater 10
includes an elongated, generally-rectangular shaped body 14 (FIGS.
4A-4D) made of a ceramic material having a first end 14A and a
second end 14B. A lengthwise axis A (FIGS. 2A, 3A and 4A) extends
through a center of the body 14 and the first and second ends 14A,
14B. The heater 10 also includes six heating elements 18 (including
a resistance wire element 18A housed within a quartz tube 18B), or
lamps, extending the length of the body 14 between the first and
second ends 14A, 14B, support plates 22 for holding the heating
elements 18 in position within the body 14, a reflector 26
positioned between the heating elements 18 and the body 14, and
mounting heads 30 for coupling the heater 10 to a housing (not
shown).
[0042] Referring to FIGS. 4A-4D, the body 14 includes a base wall
34, a first end wall 38 at the first end 14A, a second end wall 42
at the second end 14B, and first and second side walls 46, 50
extending between the first and second end walls 38, 42. The walls
34-50 define an inner cavity 54 of the body 14, which contains the
heating elements 18 and the support plates 22 of the heater 10. In
the illustrated embodiment, the base wall 34 of the body 14
includes two arc-shaped areas 56, or concave areas, for increasing
the size of the inner cavity 54.
[0043] The base wall 34 includes slots 58 for receiving the
mounting heads 30. In the illustrated embodiment, the mounting
heads 30 are oriented along the longitudinal axis A of the body 14
(FIGS. 2B and 3B), although in a further embodiment the mounting
heads 30 may be oriented perpendicularly to the longitudinal axis
A.
[0044] In the illustrated embodiment, the heater body 14 is
fabricated from an ultra-low thermal expansion ceramic material
that prevents crack formation in the body 14 when high temperature
heating elements 18 are used. Currently used ceramic heaters form
cracks and microcracks as a result of a thermal expansion mismatch
between a heating element and an outer shell. Some heating elements
can reach steady state temperatures up to 6100.degree. F. or are
rapidly energizing, which may result in thermal shock to the body,
and thereby cracks.
[0045] Thermal shock failure of ceramic bodies occurs when large
temperature gradients develop across wear sections; that is, one
side of the body expands more rapidly than an adjacent side until
the tensile strength produced on the opposite side exceeds the
strength of the ceramic body. In the illustrated embodiment, the
heater body 14 is formed from an ultra-low thermal expansion
ceramic material, which causes little to no thermal expansion of
the body either linearly or laterally. A ceramic body offers a high
degree of mechanical and thermal stability and capacity, which is
critical for fast cooling operations. When rapidly energizing
heating elements or high temperature heating elements are used,
cracking of the body 14 is prevented, and structural integrity of
the ceramic body 14 is preserved even at very fast thermal loads.
Further, the ceramic material of the body 14 keeps heat loss
through the body 14 relatively low. In the illustrated embodiment,
the ceramic material used for fabricating the body 14 includes the
formulation set forth in the table below.
TABLE-US-00001 Percentage Components (by weight) Description
Petalite 65% Lithium-Aluminum silicate China Clay 17.5% Treviscoe
china clay Ball Clay 17.5% Hymod ball clay Darvan .RTM. No. 7 0.40%
Sodium Polymethacrylate and water Water 40%
Petalite, china clay, and ball clay may be supplied by Hammill
& Gillespie (Livingston, N.J.), and Darvan.RTM. No. 7 may be
supplied by R. T. Vanderbilt Company, Inc. (Norwalk, Conn.).
[0046] It should be readily apparent to those of skill in the art
that low and ultra-low expansion ceramic material having other
chemical formulations may be used to fabricate the body 14.
Examples of other materials that may be used to for the body
includes albite, cordierite, kyanite, lepidolite, mullite,
spodumene, talc, or fused silica. For example, in one embodiment
the ceramic material includes an acrylic material to increase the
density and reduce porosity of the heater body 14. In this
embodiment, the ceramic material used for fabricating the body 14
includes the formulation set forth in the table below.
TABLE-US-00002 Percentage Components (by weight) Description
Petalite 39.78% Lithium-Aluminum silicate China Clay 10.71%
Treviscoe china clay Ball Clay 10.71% Hymod ball clay Darvan .RTM.
No. 7 0.40% Sodium Polymethacrylate and water Water 24.48%
De-ionized water Onglaze color 7.96% Series 94 lead-free onglaze
color DuramaxB-1022 4.89% Styrene/acrylic copolymer Rhoplex HA-8
1.07% Acrylic polymer
Onglaze color may be supplied by Reusche & Co. of T.W.S., Inc.
(Greeley, Colo.), and Duramax.RTM. B-1022 and Rhoplex.RTM. HA-8 may
be supplied by Rohm and Haas Company (Philadelphia, Pa.).
[0047] Universal sizes for medium-wave and long-wave ceramic
infrared heaters (i.e., the heater body) are about 60 mm by about
122 mm and about 60 mm by about 245 mm. In both embodiments, the
body has a depth of about 18 mm and a thickness of about 3 mm. In
another embodiment, the heaters may be manufactured in any
combination of both sizes, such as about 60 mm by about 367 mm (245
mm plus 122 mm). It should be readily apparent to those of skill in
the art that the body sizes may vary for custom designed radiant
heaters. For example, the body may be wider, deeper, or longer to
accommodate more heating elements, custom-sized heating elements,
or electrical circuitry. Further, the body may be thicker or
thinner depending on characteristics of the design, heating
elements and ceramic used for the body.
[0048] In one embodiment, the body 14 is fabricated from two molded
pieces defined by a box portion 62 and an upper edge portion 66, or
lip, of the body 14 (FIG. 4D). The two pieces 62, 66 are coupled
together to form a single piece such that the body 14 has a
homogenous structure. To fabricate the body 14, a first mold is
used to form the box portion 62 from the ceramic material and a
second mold is used to form the upper edge portion 66 from the
ceramic material. A ceramic cement or glue is applied to an exposed
edge of either the box portion 62 or the upper edge portion 66. One
example of the cement includes about 45% mullite-based glue. The
second mold is then placed on the first mold such that the box
portion 62 and the upper edge portion 66 meet. After a setting
period passes, the second mold is removed and the upper edge
portion 66 is connected to the box portion 62. It should be readily
apparent to those of skill in the art that other processes for
fabricating the body 14 may be used.
[0049] Referring to FIGS. 2B and 3B, the inner cavity 54 of the
body 14 is filled with a ceramic fiber 68. The ceramic fiber 68 is
positioned between the reflector 26 and the base wall 34 of the
body 14 to provide additional insulation for the heater 10. It
should be readily apparent to those of skill in the art that in
further embodiments the inner cavity 54 may be devoid of ceramic
fiber or filled with another insulating material.
[0050] Referring to FIGS. 3A-3C, the heater 10 includes six heating
elements 18 extending the length of the body 14 between the first
and second ends 14A, 14B. Each heating element 18 includes a
resistance wire element 18A housed within a clear or translucent
quartz tube 18B. FIG. 3C illustrates the heater 10 without the wire
elements or the reflector 26 to more clearly show the tubes 18B.
Referring to the embodiment shown in FIGS. 2A-2B, the radiant
heater 10 includes six resistance wire elements 18A housed in three
twin bore quartz tubes 18C.
[0051] Each wire element is housed within one bore of the tube(s).
The size of the heater body 14 may be modified to accommodate the
twin bore tubes. The resistance wire element provides medium-wave
to long-wave infrared heating and has a variable watt density from
about 10 W/in.sup.2 to about 75 W/in.sup.2 (12 W/cm.sup.2). The
wire element has an energization or heat-up time of less than one
minute. In one embodiment, the wire element is formed from a
ferritic alloy (FeCrAl); however, in a further embodiment, the wire
element may be formed from nickel chromium or a nickel chromium
alloy.
[0052] Referring to FIGS. 2A, 3A and 3C, the support plates 22 hold
and maintain the heating elements 18 within the inner cavity 54 of
the body 14. A support plate 22 is positioned at each end of the
body 14 and is coupled to the body 14 such that a portion of the
support plate 22 overlaps the respective end of the heating element
18. In the illustrated embodiment, each support plate 22 has a
generally rectangular shape and is sized to fit across the width of
the body 14. The support plate 22 is generally used in heaters of
the present invention including more than one heating element. In a
further embodiment, the support plate 22 may include recesses or
apertures for receiving the heating elements 18.
[0053] The support plate 22 is also fabricated from a hard,
insulating ceramic material, which has low thermal expansion. In
the illustrated embodiment, the ceramic material is steatite. It
should be readily apparent to those of skill in the art that low or
ultra-low expansion ceramic material having other chemical
formulations may be used to fabricate the support plate 22.
[0054] The support plates 22 are coupled to the body 14 by a high
temperature cement, or glue, that is capable of withstanding high
temperatures. A high temperature cement is necessary to prevent the
support plates 22 from separating from the body 14 at high
operating temperatures of the heating elements 18. In the
illustrated embodiment, the cement used for bonding the support
plates 22 to the body 14 includes the formulation set forth in the
table below.
TABLE-US-00003 Percentage Components (total weight) Description
Ceramabind 642 65% Inorganic, water-based binder system Glaze frit
17.5% Bismuth borosilicate and cerium oxide frit (e.g., no.
94T1001)
Ceramabind 642 may be supplied by Aremco Products, Inc. (Valley
Cottage, N.Y.), and glaze frit may be supplied by Reusche & Co.
of T.W.S. Inc. (Greeley, Colo.). It should be readily apparent to
those of skill in the art that high temperature cement having other
chemical formulations may be used to bond the support plates 22 to
the body 14.
[0055] Referring to FIGS. 2A-2B and 3A-3C, the reflector 26 is
positioned in the heater 10 between the heating elements 18 and the
base wall 34 of the body 14. FIGS. 7A-7B illustrate one embodiment
of the reflector 26 used in the radiant heater 10, which in the
illustrated embodiment is generally planar or flat. The reflector
26 re-directs heat from the heating elements 18 out of the body 14
and to a process material (not shown). By reflecting heat back to
the process material, heat loss of the heater 10 is kept relatively
low because less heat is conducted to the base wall 34 and absorbed
by the ceramic body 14. With respect to the flat reflector 26, the
fraction of the electromagnetic radiation energy reflected from a
reflective surface 70 relative to the energy incident upon the
surface 70 depends on the radiant energy wavelength and the nature
of the surface 70 and angle of incidence. Reflectivity is expressed
by Kirchhoff's law as 1-e, where e is the emissivity of the surface
70. It should be appreciated that the body 14 and the reflector 26
reduce heat loss from the heater 10, either individually or in
combination.
[0056] The reflector 26 has an elongated, generally
rectangular-shaped body that is sized to fit within the inner
cavity 54 of the heater body 14. In the illustrated embodiment, the
reflector 26 is held in place between the support plates 22, which
allows the reflector 26 to float and expand within the body 14. At
least the reflective surface 70 of the reflector 26 includes a
dome-like pattern or other recessed patterns or bumps to provide a
more specular reflection of the radiant energy. In one embodiment,
the bumps provide a greater reflection rate for the reflector
26.
[0057] In one embodiment, the reflector 26 includes a white
reflective surface, which reflects about 75% of the radiant energy
back to the process material. In further embodiments, the reflector
26 includes a gold reflective surface or a white gold reflective
surface, which reflect about 95% of the radiant energy back to the
process material.
[0058] The reflector 26 is formed from a ceramic compound base
material, such as alumina powder. To fabricate the reflector 26, a
length of alumina powder tape is cut and then embossed with a
desired pattern. In another embodiment, the pattern is applied to
the tape by stamping or scoring. It should be readily apparent to
those of skill in the art that the reflector 26 may be fabricated
without the pattern, or that any known reflective pattern may be
used for the reflector.
[0059] Next, the tape is fired or baked (e.g., at 1200.degree. C.)
such that the reflector 26 hardens. In the illustrated embodiment,
the tape is fired over a flat mold to achieve the planar surface.
In another embodiment, the reflector 26 includes a parabolic shape
and the tape is fired on a parabolic mold to achieve the parabolic
shape.
[0060] Once the reflector 26 is shaped, a glaze is added to all
surfaces of the reflector 26 and the reflector 26 is fired or baked
(e.g., 1120.degree. C.) again to bind the glaze to the reflector
body. In the illustrated embodiment, the glaze acts as the
reflective surface 70; however, in a further embodiment, the glaze
provides a binder for applying the gold, white gold, or other
reflective material. Due to the high amount of heat generated by
the heating elements 18, the glaze keeps the reflective material
bound to the reflector body at high temperatures. In the
illustrated embodiment, the glaze used for the reflector 26
includes the formulation set forth in the table below.
TABLE-US-00004 Percentage Components (by weight) Description Clear
Glaze 35.6% Glaze frit (e.g., ENQ9144E/P1) Cristobalite 1.2% Silica
powder 325 mesh VeeGum .RTM. 1.5% Suspending agent
Clear glaze may be supplied by Johnson Matthey (Downington, Pa.),
cristobalite may be supplied by CED Process Minerals (Tallmage,
Ohio), and VeeGum.RTM. suspending agent may be supplied by R. T.
Vanderbilt Company, Inc. (Norwalk, Conn.). It should be readily
apparent to those of skill in the art that glaze having other
chemical formulations may be used for the reflector 26.
[0061] If an additional reflective material is to be applied to the
reflector 26, the material is added after the glaze is fired onto
the reflector body. In one embodiment, the reflective material is
sprayed onto the reflector 26 using an industrial spray system, as
is known in the art. A gold reflective material is comprised of 24
caret gold and a white gold reflective material is comprised of
about 90% 24 caret gold and about 10% platinum. In one embodiment,
about 0.825 grams of reflective material are required to coat the
reflective surface of the reflector 26. After the reflective
material is applied to the reflector 26, the reflector 26 is fired
or baked (e.g., 850.degree. C.) again to bind all the materials
together.
[0062] Referring to FIGS. 2B and 3B, the heater 10 includes the
mounting heads 30 for coupling the heater 10 to a housing (not
shown). The mounting heads 30 are coupled to an exterior surface
34A of the base wall 34 of the body 14. The mounting heads 30 are
formed from a ceramic material, such as non-porous lava ceramic. A
high temperature cement is necessary to prevent the mounting heads
30 from separating from the body 14 at high operating temperatures
of the heating elements 18. In the illustrated embodiment, the
cement used for bonding the mounting heads 30 to the body 14
includes the formulation set forth in the table below.
TABLE-US-00005 Percentage Components (by weight) Description
Ceramabind 642 65% Inorganic, water-based binder system Black Glaze
35% Glaze frit (e.g., ENQ10615E/P1)
Ceramabind 642 may be supplied by Aremco Products, Inc. (Valley
Cottage, N.Y.), and black glaze may be supplied by Johnson Matthey
(Downington, Pa.). It should be readily apparent to those of skill
in the art that high temperature cement having other chemical
formulations may be used to bond the mounting heads 30 to the body
14.
[0063] To couple the heater 10 to a housing, the mounting head 30
is received by the slot 58 in the housing and a mounting spring
clip 74 is coupled to a free end 30A of the head 30 to hold the
heater 10 in position, as is known in the art. One example of the
spring clip 74 is shown in FIG. 8.
[0064] FIGS. 5, 6 and 9 illustrate other embodiments of a body for
the radiant heater 10 shown in FIGS. 2A-2B and 3A-3C. FIG. 5
illustrates a body 78 for the radiant heater 10 including apertures
82 for coupling an element holder, as discussed below. FIG. 6
illustrates a body 86 for the radiant heater 10 including the
apertures 82 for the element holder, and convection holes 90 for
dispersing heat or energy from the heater 10, as discussed below.
FIG. 9 illustrates a body 94 of the radiant heater 10 including a
modified inner cavity 98 for receiving the twin bore heating tubes
with wire elements shown in FIGS. 2A-2B.
[0065] FIGS. 10A and 10B illustrate a radiant heater 110 according
to another embodiment of the invention. The radiant heater 110 is
similar to the radiant heater 10 shown in FIGS. 2A-2C and 3A-3C,
therefore, like elements will be identified by the same reference
numerals. The radiant heater 110 includes the elongated,
generally-rectangular shaped body 14 made of a ceramic material, a
heating element 114 extending the length of the body 14 between the
first and second ends 14A, 14B, element holders 118 for holding and
supporting the heating elements 114 in position within the body 14,
a reflector 122 positioned between the heating elements 114 and the
body 14, and the mounting heads 30 for coupling the heater 110 to a
housing (not shown).
[0066] Referring to FIGS. 12 and 13, the heater 110 includes
convection holes 126 formed in the base wall of the body 14. The
convection holes 126 provide a through path for fumes generated by
the process material during use of the radiant heater 110, for
example when the heater 110 includes short-wave heating elements
114. The convection holes 126 minimize the accumulation of fumes in
the cavity area of the heater by dispersing fumes through the holes
126. An accumulation of fumes may affect the physical
characteristics of the process material. The convection holes 126
are located based upon the base wall of the body, the heating
elements, and the process material location for sufficiently
dispersing fumes.
[0067] In the illustrated embodiment, the heater body 14 is
fabricated from an ultra-low expansion ceramic material that
prevents cracks from forming in the body 14 when high temperature
heating elements 114 are used. One example of the ceramic material
is discussed above with respect to the radiant heater 10 shown in
FIGS. 2A and 3A.
[0068] The radiant heater 110 includes one heating element 114
extending the length of the body 14 between the first and second
ends 14A, 14B. The heating element 114 includes a halogen-tungsten
element 130 housed within a quartz tube 134. The halogen-tungsten
lamp 114 is also referred to as a halogen lamp. The
halogen-tungsten element 130 provides short-wave infrared heating
and has a watt density of about 190 W/in.sup.2 (29 W/cm.sup.2). The
halogen-tungsten element 130 has an energization, or heat-up, time
of about two seconds. In one embodiment, the halogen-tungsten
element is formed with clear or transparent high purity quartz
material. In another embodiment, the halogen-tungsten element 130
is housed within a ruby quartz tube, which absorbs the visible
light emanating from the element 130 while transmitting most of the
infrared energy.
[0069] Element holders 118 hold and maintain the heating element
114 within the inner cavity 54 of the body 14. One element holder
118 supports each end of the heating element 114 adjacent opposite
ends 14A, 14B of the heater body 14. The element holders 118 are
also fabricated from a hard, insulating ceramic material, which has
low thermal expansion. In the illustrated embodiment, the ceramic
material is steatite. It should be readily apparent to those of
skill in the art that zero expansion ceramic material having other
chemical formulations may be used to fabricate the element holders
118.
[0070] Referring to FIGS. 14A-14C and 15, the element holder 118
includes a body portion 138 having a pair of upwardly extending
flanges 142, 146 and a pair of downwardly extending projections
150, 154. The flanges 142, 146 define a channel 158 for receiving
one end of the heating element 114. In one embodiment, the heating
element 114 is maintained within the channel 158 by a friction fit
or pressure fit, although other mechanisms for securing the heating
element 114 within the channel 158 may be used. In a further
embodiment, the heating element 114 is placed within the channel
158, and the wire element extends from the heating element and is
coupled to the mounting head 30 to hold the heating element 114 in
place. The body portion 138 includes an outwardly extending
shoulder 162 that may be used to retain the reflector 122 within
the body 14.
[0071] To couple each element holder 118 to the body 14 of the
heater 110, the first projection 150 is retained in an aperture 166
(FIG. 12) formed in the base wall 34 of the body 14. In one
embodiment, the projection 150 may be secured to the body 14 by a
friction or pressure fit, or a high temperature cement. It should
be readily apparent to those of skill in the art that a second
aperture may be formed in the base wall 34 for retaining the second
projection 154. To further secure the element holder 118 to the
body 14, a high temperature cement, or glue, that is capable of
withstanding high temperatures bonds the element holder 118 to the
body 14. High temperature cement is necessary to prevent the
element holders 118 from separating from the body 14 at high
operating temperatures of the heating elements 114. One example of
the cement is discussed above with respect to the support plates 22
for the radiant heater 10 shown in FIGS. 2A and 3A.
[0072] In another embodiment an additional mechanical means may be
used to couple the element holder to the heater body. For example,
the element holder 118 includes the pair of downwardly extending
projections 150, 154, and the first projection 150 includes a slot
therethrough for receiving a mechanical fastener (not shown).
Further, at least the first projection 150 has a greater length to
facilitate attachment. To couple the element holder 118 to the body
14 of the heater 110, the first projection 150 is retained in the
aperture 166 formed in the base wall 34 of the body 14 and a wire
fastener clip (not shown) slides through the slot of the first
projection 150 to keep the element holder 118 from falling out of
the heater body 14. In one embodiment, the projection 150 may be
secured to the body 14 by a friction or pressure fit. As discussed
above with respect to FIGS. 14A-14C, to further secure the element
holder 118 to the body 14, a high temperature cement, or glue, that
is capable of withstanding high temperatures bonds the element
holder 118 to the body 14.
[0073] The reflector 122 is positioned in the heater 110 between
the heating elements 114 and the base wall 34 of the body 14. FIGS.
16A and 16B illustrate one embodiment of the reflector 122 used in
the radiant heater 110, which in the illustrated embodiment has a
generally parabolic shape. With respect to the parabolic reflector
122, the parabola has the equation, y.sup.2=4px, where a focal
point of the parabola is at (0,p). The distance p becomes critical
when a reflective surface 170 is gold coated. The equation for the
parabola should consider the average thickness of the reflector
122. To form the parabolic reflector 122, the reflector 122 is
fabricated as discussed above with respect to FIGS. 7A and 7B;
however, the alumina tape is fired on a parabolic mold to achieve
the parabolic shape. The reflector mold is designed based upon the
desired parabolic shape, focal point for the application, and
desired distance between the reflector 122 and the heating element
114.
[0074] The reflector 122 has an elongated, generally
parabolic-shaped body that is sized to fit within the inner cavity
54 of the heater body 14. In the illustrated embodiment, the
reflector 122 is held in place by the element holders 118, which
allows the reflector 122 to float and expand within the body 14.
Referring to FIGS. 10A and 15, the reflector 122 may slide
longitudinally and laterally within the inner cavity 54; however,
the ends of the reflector 122 slide within a channel 174 (FIG. 15)
defined by the shoulder 162 of the element holder 118 and the body
14. In the illustrated embodiment, each end of the reflector 122
includes a pair of projections 176. When the radiant heater 10 is
assembled, the projections 176 of the reflector 122 are received by
the channel 174 defined by the element holder 118 to hold the
reflector 122 in the heater body 14. Further, the elements holders
118 allow spacing between the reflector 122 and the base wall 34 of
the body 14, which provides an air gap insulator through the heater
110.
[0075] At least the reflective surface 170 of the reflector 122
includes a dome-like pattern or other recessed patterns or bumps to
provide a more specular reflection of the radiant energy. In one
embodiment, the bumps provide a greater reflection rate for the
reflector 122. In one embodiment, the reflector 122 includes a gold
reflective surface. In further embodiments, the reflector 122
includes a white gold reflective surface. In still another
embodiment, the radiant heater 110 includes a reflector 122 having
a white reflective surface, which is formed by the reflector glaze
(as discussed above).
[0076] In a further embodiment, a pair of projections are bonded to
the reflective surface 170 of the reflector 122 to allow the
reflector 122 to move laterally within the body 14 and keep the
parabolic reflector 122 centered within the body 14. The
projections may be fabricated from a hard, insulating ceramic
material, which has low thermal expansion. In the illustrated
embodiment, the ceramic material is steatite. To secure the
projections to the reflective surface 170 of the reflector 122 a
high temperature cement, or glue, that is capable of withstanding
high temperatures bonds the projections to the reflector 122. A
high temperature cement is necessary to prevent the projections
from separating from the body 14 at high operating temperatures of
the heating elements 114. One example of the cement is discussed
above with respect to the support plates 22 for the radiant heater
10 shown in FIGS. 2A and 3A.
[0077] FIGS. 11A and 11B illustrate a radiant heater 210 according
to another embodiment of the invention. The radiant heater 210 is
similar to the radiant heater 110 shown in FIGS. 10A-10B,
therefore, like elements will be identified by the same reference
numerals. The radiant heater 210 includes a pair of heating
elements 114 extending the length of the body 14 between the first
and second ends 14A, 14B, each heating element 114 supported by a
pair of element holders 118. Each heating element 114 includes a
halogen-tungsten element 130 housed within a quartz tube 134. In
the illustrated embodiment, the halogen-tungsten heating elements
114 are spaced apart. The use of two halogen-tungsten elements 114
allows customization of the wavelength and resultant radiant energy
of the heater 210. In another embodiment, the halogen-tungsten
elements 114 are housed within ruby quartz tubes, which diminish
the light emitted from the heating element 114.
[0078] Referring to FIG. 17, the heater 210 includes two pairs of
apertures 214 at each end of body 14 for receiving the respective
element holders 118. The body 14 also convection holes 126 formed
in the base wall 34 of the body 14 for dispersing fumes, as
discussed above.
[0079] The radiant heater 210 shown in FIGS. 11A and 11B includes a
flat reflector 218 for re-directing heat from the heating elements
114 out of the body 14 and to a process material (not shown), as
described above with respect to FIGS. 7A-7B. In the illustrated
embodiment, the flat reflector 218 is used rather than the
parabolic reflector 122 due to the number of heating elements 114
in the body 14.
[0080] In one embodiment, the reflector 218 includes a gold
reflective surface. In further embodiments, the reflector 218
includes a white gold reflective surface, and in still another
embodiment, the radiant heater 210 includes a reflector 218 having
a white reflective surface, which is formed by the reflector glaze
(as discussed above).
[0081] FIGS. 18A and 18B illustrate a radiant heater 310 according
to another embodiment of the invention. The radiant heater 310 is
similar to the radiant heater 110 shown in FIGS. 10A and 10B,
therefore, like elements will be identified by the same reference
numerals. The radiant heater 310 includes a heating element 314
extending the length of the body 14 between the first and second
ends 14A, 14B. The heating element 314 includes a carbon element
318 housed within a quartz tube 322. The carbon element 318
provides medium-wave infrared heating and has a watt density of
about 75 W/in.sup.2 (12 W/cm.sup.2). The carbon element 318 has an
energization, or heat-up, time of about two seconds.
[0082] The heating element 314 is supported by a pair of element
holders 118, as described above. Referring to FIG. 12, the heater
310 includes an aperture 166 at each end of body 14 for receiving
the respective element holder 118. The body 14 also includes
convection holes 126 formed in the base wall 34 of the body 14 for
dispersing fumes, as described above.
[0083] The radiant heater 310 shown in FIGS. 18A and 18B includes a
parabolic reflector 326 for re-directing heat from the heating
elements 314 out of the body 14 and to a process material (not
shown), as described above. The reflector 326 may include a gold
reflective surface, a white gold reflective surface or a white
reflective surface, which is formed by the reflector glaze, as
described above.
[0084] FIGS. 19A and 19B illustrate a radiant heater 410 according
to another embodiment of the invention. The radiant heater 410 is
similar to the radiant heater 310 shown in FIGS. 18A and 18B,
therefore, like elements will be identified by the same reference
numerals. The radiant heater 410 includes a pair of heating
elements 314 extending the length of the body 14 between the first
and second ends 14A, 14B. Each heating element 314 is supported by
a pair of element holders 118. Each heating element 314 includes a
carbon element 318 housed within the quartz tube 322. In the
illustrated embodiment, the carbon heating elements 314 are spaced
apart. The use of two carbon elements 318 allows customization of
the wavelength and resultant radiant energy of the heater 410.
[0085] Referring to FIG. 17, the heater 410 includes two pairs of
apertures 214 at each end of body 14 for receiving the respective
element holders 118. The body 14 also includes convection holes 126
formed in the base wall 34 of the body 14 for dispersing fumes, as
described above.
[0086] The radiant heater 410 shown in FIGS. 19A and 19B include a
flat reflector 414 for re-directing heat from the heating lamps 314
out of the body 14 and to a process material (not shown), as
described above. In the illustrated embodiment, the flat reflector
414 is used rather than the parabolic reflector due to the number
of heating elements 314 in the body 14. The reflector 414 may
include a gold reflective surface, a white gold reflective surface,
or a white reflective surface, which is formed by the reflector
glaze, as described above.
[0087] FIGS. 20A and 20B illustrate a radiant heater 510 according
to another embodiment of the invention. The radiant heater 510 is
similar to the radiant heater 310 shown in FIGS. 18A and 18B,
therefore, like elements will be identified by the same reference
numerals. The radiant heater 510 includes three heating elements
314 extending the length of the body 14 between the first and
second ends 14A, 14B. Each heating element 314 includes a carbon
element 318 housed within the quartz tube 322. In the illustrated
embodiment, the carbon heating elements 318 are spaced apart. The
use of three carbon elements 318 allows customization of the
wavelength and resultant radiant energy of the heater 510.
[0088] Each heating element 314 is supported by a pair of element
holders 118 and two supports plates 22 help maintain the heating
elements 314 in the body 14. Referring to FIG. 17, the heater 510
includes three pairs of apertures 214 at each end of body 14 for
receiving the respective element holders 118. The body 14 also
includes convection holes 126 formed in the base wall 34 of the
body 14 for dispersing fumes, as described above. One support plate
22 is positioned at each end of the body and is coupled to the body
such that a portion of the support plate 22 overlaps ends of the
heating elements 314.
[0089] The radiant heater 510 shown in FIGS. 20A and 20B includes a
flat reflector 518 for re-directing heat from the heating elements
314 out of the body 14 and to a process material (not shown), as
described above. In the illustrated embodiment, the flat reflector
518 is used rather than the parabolic reflector due to the number
of heating elements 314 in the body 14. The reflector 518 may
include a gold reflective surface, a white gold reflective surface,
or a white reflective surface, which is formed by the reflector
glaze, as described above.
[0090] The present invention radiant heater allows heating elements
having different wavelengths to be used in a single unit. For
example, in one embodiment a single heater may include two heating
elements, one delivering short-waves and one delivering
medium-waves. Therefore, a radiant heater may deliver short, medium
or long waves as a single unit by utilizing different heating
elements. The use of multiple elements having different wavelengths
allows customization of the wavelength and resultant radiant energy
of the heater.
[0091] FIGS. 21A and 21B illustrate a radiant heater 610 according
to another embodiment of the invention. The radiant heater 610 is
similar to the radiant heaters 210 and 410 shown in FIGS. 11A-11B
and 19A-19B, therefore, like elements will be identified by the
same reference numerals. The radiant heater 610 includes a pair of
heating elements 614A, 614B extending the length of the body 14
between the first and second ends 14A, 14B, each heating element is
supported by a pair of element holders 118. One heating element
614A includes a halogen-tungsten element 618 housed within a quartz
tube 622 and the other heating element 614B includes a carbon
element 626 housed within a quartz tube 622. In the illustrated
embodiment, the heating elements 614A, 614B are spaced apart. In
another embodiment, the halogen-tungsten element 618 is housed
within a ruby quartz tube, which diminishes the light emitted from
the heating element 614A.
[0092] Referring to FIG. 17, the heater 610 includes two pairs of
apertures 214 at each end of body 14 for receiving the respective
element holders 118. The body 14 also includes convection holes 126
formed in the base wall 34 of the body 14 for dispersing fumes, as
described above.
[0093] The radiant heater 610 shown in FIGS. 21A and 21B include a
flat reflector 630 for re-directing heat from the heating elements
614A, 614B out of the body 14 and to a process material (not
shown), as described above. In the illustrated embodiment, the flat
reflector 630 is used rather than the parabolic reflector due to
the number of heating elements in the body 14. The reflector 630
may include a gold reflective surface, a white gold reflective
surface, or a white reflective surface, which is formed by the
reflector glaze (as discussed above).
[0094] FIGS. 22A and 22B illustrate a radiant heater 710 according
to another embodiment of the invention. The radiant heater 710 is
similar to the radiant heaters 310 and 610 shown in FIGS. 20A-20B
and 21A-21B, therefore, like elements will be identified by the
same reference numerals. The radiant heater 710 includes three
heating elements 614A, 614B, 614C extending the length of the body
14 between the first and second ends 14A, 14B. The center heating
element 614A includes a halogen-tungsten element 618 housed within
the quartz tube 622 and the outer heating elements 614B, 614C
include a carbon element 626 housed within a quartz tube 622. In
another embodiment, the halogen-tungsten element 618 is housed
within a ruby quartz tube, which diminishes the light emitted from
the heating element 614A.
[0095] Each heating element 614A-614C is supported by a pair of
element holders 118 and two supports plates 22 help maintain the
heating elements in the body 14. Referring to FIG. 17, the heater
710 includes three pairs of apertures 214 at each end of body 14
for receiving the respective element holders 118. The body 14 also
includes convection holes 126 formed in the base wall 34 of the
body 14 for dispersing fumes, as described above. One support plate
22 is positioned at each end of the body 14 and is coupled to the
body 14 such that a portion of the support plate 22 overlaps ends
of the heating elements 614A-614C.
[0096] The radiant heater 710 shown in FIGS. 22A and 22B includes a
flat reflector 714 for re-directing heat from the heating elements
614A-614C out of the body 14 and to a process material (not shown),
as described above. In the illustrated embodiment, the flat
reflector 714 is used rather than the parabolic reflector due to
the number of heating elements in the body 14. The reflector 714
may include a gold reflective surface, a white gold reflective
surface, or a white reflective surface, which is formed by the
reflector glaze (as discussed above).
[0097] It should be appreciated that in radiant heaters utilizing
multiple heating elements, the elements may be energized separately
to further customize the wavelength and resultant radiant energy of
the heater. In one embodiment, energization and de-energization of
the heating elements (individually or in combination) is initiated
and controlled by a controller.
[0098] It should also be appreciated that the radiant heater
components described above may be utilized to fabricate customized
heaters. For example, a user may designate a desired wavelength,
resultant radiant energy, body size, structural housing, or the
like, and a radiant heater can be built to the desired
specifications using the universally sized bodies, the element
holders, the support plates, the mounting heads, the reflectors,
and heating elements.
[0099] The embodiments described above and illustrated in the
figures are presented by way of example only and are not intended
as a limitation upon the concepts and principles of the present
invention. As such, it will be appreciated by one having ordinary
skill in the art that various changes in the elements and their
configuration and arrangement are possible without departing from
the spirit and scope of the present invention.
* * * * *